Acoustic apparatus for detecting sound-vibrations in non-gaseous media.



n.v w. Ams. ACOUSTIC APPARATUS FOR DETECTING SOUND VIBRATIONS IN NON-GASEOUS MEDIA.

APPLICATION FILED MAY15, 1909. RENEWED JAN. 22,1910.

` Patented Ag. 10, 1915.

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DEXTER W. ALLIS, OEREVEBE, MASSACHUSETTS, ASBIGNOR, BY MESNE ASSIGNMENTS, TO BOSTON TALKING MACHINE COMPANY, OF BOSTON, MASSACHUSETTS, A CORPO'- RATION OF MAINE,

ACOUSTIC APPARATUS FOB DETECTING SOUND-VIBRATIONS IN NON-GASEOUS MEDIA.

Specication of Letters fatent. v i Patented Aug. 10, 1915.

Oontinuation of application 'Serial No. 420,510, led March 11.1908. This application led May 15, 1909, Serial' No. 496,161. Renewed January 22,'1910. Serial No. 538,602.

To all whom, it may concern: A

Be it known that I, DEXTER W. ALLIs, a citizen of the United States, residing at Revere, in the county of Essex and State of Massachusetts, have invented an Improvement in Acoustic Apparatus for Detecting Sound-Vibrations in Non-Gaseous Media, of which the following description, in connection with the accompanyingl drawings, is a specification, like letters on the drawings representing like parts.

My invention relates to acoustic apparatus for detecting sound vibrations in nongaseous media, as distinct from gaseouslyl remain unresponsive to gaseously transmittedy sound vibrations. Such member may be held in contact with a solid or liquid body through which sound vibrations are conducted, and serve to transmit the sound vibrations through the walls of the contact member to an associated microphone of any ordinary construction, which latter is appropriately insulated against all sound vibrations except those received through the contact member by reason of its contact with the vibrating solid or liquid body. The disturbance thus caused in the insulated microphone may be utilized to vary the resistance of an electric current and thereby to create electric undulations corresponding to the sound vibrations in the solid contact member, such electric undulations being transmitted to a telephone receiver by suitable conductors passing through the sound insulated inclosure of the microphone. I

Such invention may have useful application for many different purposes, such, for example, as the detection of leaks in liquid conducting pipes, the investigation of broken bearings in shafts or axles, or the accuracy mitted through the surrounding atmosphere or other gaseous medium.

The invention will be best understood by reference to the following-description when taken in connection with the4 accompanying illustration of one specic embodiment thereof, while its scope will be more particularly pointed out in the appended claims.

In the drawings: Figure l shows a form of portable apparatus embodying one form of my invention; Fig. 2 is a central, vertical section on the line 2 2 in Fig. l; and Fig. 3 is a similar section on the line 3 3 in Fig. 2. I While the apparatus which forms the sub- ]ect 'matter of my invention may be constructed in various ways and may be either portable or non-portable according to the purpose'to which it is'applied, inthe form which for illustrativepurposes is shown in Fig. l it consists of a portable device having the handle l, the latter connected by the stem 2 to a contact member 3. Thelatter may be of any desired shape, presenting convtact walls of any desired area, and may be of any suitable material -properly to respond by contact to the soundnvibrations of solid or liquid bodies, while being non-responsive to the sound vibrations of the surrounding atmosphere or other gaseous media. Herein, however, it is preferably of metal, such as -iron or brass, and is rounded as shown to permit its ready application by Contact to 4the bearing of a shaft or to any other object or body, the sound vibrations of which are to be detected.

For the purpose of insulating the microphone, .the contact member herein is constructed in the form of a casing or inclosure. This consists of the main body portion 4, which has its open end herm'etically sealed by means of a plate 5 soldered to the casing and provided with a threaded stud 6, which is engaged by the nut 7, the latter serving to hold in position the outer closure 8. The walls of the closure are purposely formed of a sufficient thickness and mass so that it isinca'pable vof vibrating as a dlal phragmror otherwise in response to any orof cotton or otherl suitable -material.

dinary air vibrations or other" vibrations transmitted through the gaseous medlum 1n which the casing is placed. When placed vin contact with a solid or liquid body, however, sound vibrations may be readily communicated therefrom to the solid and relatively thick Wa'lls of the casingand the latter will act as a transmitter to cause a d1sturbance in the microphone inclosed within the same. i,

The vmicrophone may be of any desired construction so long as itis acoustically associated with thesolid contactl member, my invention broadly considered havingno particular reference to. the detail construction of thev microphone itself. In the particular form shown inthe drawings a common form of microphone button is illustrated rigidly and mechanically attached to the inner walls of the contact member by means of the threaded shank 9. The latter supports the xed carbon contact Vor electrode 10 for the microphone, there being provided a mica diphragm 11 held against the outer face ofthe carbon electrode by means of a washer 12 and nut 13. The mica disk supports the thin cup-shaped casing 14 for the button, to the; inner. end wallof which is which, together with the electrode, are held in place by the surrounding annular rinIg 17 t is not necessary that the microphone should be surrounded wholly by the walls of the contact member so long as it is suitably insulated against gaseously transmitted sound vibrations and so l'ong as the contact memb er, whatever may be its shape or exposed area, is capable of transmitting its contacthandle 1 where it is connected to the bat, tery cells 2O and 21, which are conveniently received vibrations to the microphone.

For the microphone there are provided suitable connections to an appropriate listening device. be electrically insulated from the casing, if

desired, herein the electrode 10, being at tached to the casing, is electrically connected thereto and the casing is included in one side ofthe circuit. Thel other electrode 15 is connected to the microphone casing 14 and the latter to the conductor 18, which is em-v bedded in an insulating tube 19 fitting tightly within the connecting stem 2. The conductor passes through the stem to the While the microphone may.

26. .The latter contacts with the' lplate 27 connected to the binding post 28, which latter p asses through a sleeve 29, insulating lthe vbinding post from the handle casing 1. A

second binding post 30 is threaded into the end of the handle casing so that it has metallic connection through the casing and the contact member with lthe electrode 10.

-' Any suitable listening device may be employed, but herein Ihave utilized a. pair of head telephone receivers 31 and 32v connected together by a resilient band 33 adapted to hold the receivers in position against the ears of the listener. The two receivers are connected in series' by the insulated conductor. 34 which connects a terminal on one receiver to a terminal on the other, the remainingterminals being connected, respectively, by the insulated conductors 35 and I vin which are to be'tested. If, forexample,

this is the bearing of a shaft, lthe sound heard at 'the `transmitter willl result exclu- -K sively from the sounds transmitted through the walls of the bearing against 4which the contact member rests and none of the sounds externall thereto and transmitted through the air will in any way affect the microphone or'be manifested 'at the receiver. If the shaft .is runningA evenly'and true the sound transmitted will indicate this, but if running unevenly or out of alinement the irregular sound transmitted will at once indicate the fact, and the degree of irregularity in running will also be evident. The microphone being unresponsive wholly to air vibrations, such a test, so far as the transmitting qualities of the instrument are concerned, may be conducted in a noisy workshop and in the midst of the greatest din and noise as readily as in a quiet room.

This example is merely illustrative of numerous uses to which the apparatus may be applied. Another example of its application is for the detection of leaks in water or other liquid-conducting pipes. When the pipe is intact and water flowing regularly through it, this fact can readily be determined by contact withI the pipe or other -solid body associated therewith. When thereis a break or other leak in the pipe, however, and: there is an abnormal flow of water, the contact between the conductor and the pipe, or any spot in its vicinity, will enable the listener to discover it from the sound iii"" tlie" receiver.

It is to be understood that my invention loo has extensive ap lication to purposes widely different from t ose suggested, and is susceptible of embodiment in a great variety of forms without departing from the spirit of the invention.

Having thus described my invention, what I claim is; A

1. In an apparatus of the class described, the combination of a portable completely closed casing for contact with a solid body, a microphone contained in said casing and connected to a suitable receiver, said casing being sufficiently rigid and thick to insulate the microphone from external sounds except those received by contact and a vibration-conducting connection projecting 1nward from said casing and secured to said microphone substantially in axial line with the vibratory center of said microphone.

2. An apparatus of the class described comprising in combination, an electro-microphone detector connected to a suitable receiver, a metallic contact casing entirely inclosing said detector and of a suitable thickness to insulate the detector from external sounds excepting those received by Contact -between said casing and a solid body, and

vibration-conducting. means rigidly connected to said casin and to said microphone, substantially 1n line with the point of maximum vibration of the latter.

3. A portable sound-detecting device comprising a closed contact casing having thick, rigid, walls for insulating the interior thereof from external sounds except those received by contact between said casing and a solid body, a microphone contained in said casing, and an element constituting a rigid connection between said -casing and said microphone for conducting vibration from the former to the latter.

4. A portable sound detecting device comprising a small closed metallic casing consisting of thick walls for insulating the interior of said casing from external Sounds, `excepting those received by contact between said casing and a solid body, a microphone slightly smaller than said casing contained in the latter' and an element rigidly connecting said microphone with a wall of said casing and constituting the sole supporting means for said microphone.

5. A portable sound-detecting device comprising a metallic closed contact casing having thick walls for insulating the interior thereof from external sounds, excepting those received by contact between said casing and a solid body, a microphone contained in said casing comprising a casing having a fixed electrode and a movable electrode, and a rigid connection between said iixed electrode and an inner wall of said contact casing. Y

6. In an article of the class described, the combination of a portable device comprising a casing having integral therewith a contact wall and containing a battery' and a transmitter in electric circult, said trans-- `mitter being secured to the inner face of said Contact wall of said casing, a receiver, and wire connections between said device and receiver.

7 In an article ofthe class described, the combination of a portable casing having a closed chamber at one end, one end wall of which is integral with said casing, while the opposite wall is hermetically sealed thereto, a battery in a second chamber in said casing, a transmitter secured to the first-mentioned wall, a receiver, and means for connecting said receiver, battery and transmitter in electric circuit.

8. In an article of the class described, the combination of a portable casing having a handle at one end and a chambered member at the opposite end, one'end wall of which is integral with said casing and provided with. an outer contact surface extending beyond all other parts of said casing, a battery in and insulated from Said handle, a transmitter suspended in said chambered member, an electric connection between said transmitter and casing, an electric connection between said transmitter and battery insulated from said casing, a receiver, and electric connections between said receiver and casing and said receiver and battery.

9. In an article of the class described, the combination of a portable casing having a handle lat one end and a chambered member at the opposite end, one end wall of which is integral with said casing and provided with an outer contact surface extending beyond all other parts of said casing, a battery in and insulated from said handle, a member extendinginwardly from one wall of said chamber, a transmitter suspended thereon, an electric connection between said transmitter and casing, an electric connection between said transmitter and battery insulated from said casing, a receiver, and

electric connections between said receiver'l and casing and said receiver and battery.

l0. In an article of the class described, the combination of a portable casing having a handle at one end and a hermetically sealed chamber at the opposite end, a battery in and insulated from said handle, a

member extending inwardly from one wall ter in circuit.

beyondA all other parts of said casing, a In testimony whereof, I have signed my transmitter in said chamber, one velectrode name to this specification, in the presence of 10 -of which is connected to said casing, 'a hantwo subscribing witnesses.

die for said casing a battery4 therein con# .i5 nected to the other electrode and insulated f l DEXTER W ALLIS' fromv said casing, 'a receiver, and Wirescon- Witnesses: I necting said receiver, battery' and transmti GEORGE E. EAMES,

THOMAS B. Boo'rH. 

